The present invention relates to a post-treatment device for carrying out treatments such as accumulating a plurality of sheets discharged from an image forming apparatus such as a copying device or a printer to match them, and stapling (staple) a bundle of sheets thus matched, and an image forming apparatus provided with such a sheet post-treatment device as described.
The image forming apparatus receives image data to be printed from a data treatment device, for example, such as an image reading device, a facsimile device, or a computer, to form a printed image on the sheet on the basis thereof.
The sheet post-treatment device receives a sheet after image formation from the image forming apparatus to discharge it onto a sheet discharge tray. However, in case where a plurality of sheets after image formation are present, ends of a bundle of sheets are matched; or the ends of a bundle of sheets are subjected to stapling as necessary; and as the case may be, post-treatment such as boring a punch hole is carried out. The bundle of sheets applied with such a post-treatment as described is finally stacked sequentially on the accumulation tray, and taken out by an operator.
However, some image forming apparatuses are of the type in which where one set of a plurality of sheets after image formation is received by the post-treatment device to stack them, the sheets are discharged in the state that both sides of the sheet are reversed.
Accordingly, it is necessary for the sheet post-treatment device used for such an image forming apparatus as described to provide, internally thereof, a switch-back mechanism for inverting both sides of a sheet before a series of sheets are accumulated and matched.
In such a switch-back mechanism as described, normally, a switch-back route need be secured without fail within the post-treatment device, and therefore, the sheet post-treatment device having a switch-back function should have been formed into a larger size.
However, it has been pressed greatly that peripheral optional apparatuses as well as the sheet post-treatment device are necessarily made into a type as small as possible without impeding readiness of taking out sheets while adjusting to the miniaturization of the image forming apparatus itself.
Further, where the switch-back for inverting both sides of a sheet is carried out inside the device, since the switch-back is to be carried out in a narrow bended space within the device, jamming tends to occur. Further, since in taking out the sheet jammed within the device, the switch-back route within the device has to be placed in an open state, the taking-out work was cumbersome.
Furthermore, since the shape of a sheet is changed, or accessories are add to the sheet whereby the post-treatment is applied to the sheet, the jam tends to occur, and where the jam occurs actually, securing of readiness of releasing the jam in a portion for carrying out the post-treatment such as staple or punch in which treatment of releasing the jam is more difficult than the switch-back route is all extremely important design matter for the sheet post-treatment device and the image forming apparatus.
It is therefore an object of the present invention to provide a sheet post-treatment device in which a sheet post-treatment device having a switch-back function as described above is realized in an extremely compact size without impeding the readiness of taking out sheets, and possibility of occurrence of jams in a portion where switch-back is carried out and a portion for applying post-treatment to a sheet is greatly reduced, and even if the jam should occur at the worst, one can cope therewith easily.
Therefore, the present invention provides a sheet post-treatment device, comprising: sheet carrying-in means for receiving a sheet discharged from an image forming apparatus: switch-back means for switch-back conveying the sheet received from the sheet carrying-in means; inversion means for inverting both sides of the sheet received from the switch-back means; discharge means for discharging the sheet whose both sides are inverted by the inversion means; loading means provided upward of the switch-back means to load the sheet discharged by the discharge means; post-treatment means for post-treating the sheet loaded on the loading means; and housing means for housing tile sheet subjected to post-treatment by the post-treatment means.
Thereby, in the present invention, since the switch-back means is housed in a lower space of the treating tray necessitated originally, it is possible to have a size nearly similar to that of a sheet post-treatment device having no switch-back function, and the loading means for applying post-treatment by which jam treatment is difficult is arranged upward of the switch-back means to facilitate the jam treatment.
Further, since the switch-back means is formed in a straight line, and at least one of them is exposed, jam is hard to occur in a sheet, and even if the sheet jam should occur at the worst, one can deal therewith by easy constitution.
The present invention is characterized in that the post-treatment means comprises a post-treatment unit for applying prescribed treatment to a sheet load on the loading means, and moving means for moving the post-treatment unit along one end of the sheet loaded on the loading means.
Thereby, the complicated post-treatment unit having the moving constitution is installed upward of the switch-back means, and one can deal therewith by easy constitution.
The present invention is characterized in that at least one of the post-treatment means and the moving means is arranged within a region surrounded by the switch-back means, the inversion means, and the loading means.
Thereby, the post-treatment device or the moving means for moving the post-treatment device is arranged making use of a region or space surrounded by the switch-back means, the inversion means, and the loading means. The device can be further miniaturized.
The present invention is characterized in that the inversion means is constituted by a nearly -shaped conveying route provided between the switch-back means and the loading means.
Thereby, the switch-back means and the loading means can be provided on the same side with respect to the inversion means, the device can be further miniaturized as compared with the case where the switch-back means and the loading means are provided in an opposing direction with the inversion means put therebetween. Further, a space whose three sides are surrounded by the nearly -shaped conveying route can be prepared, in which space the post-treatment means or the means for moving the post-treatment means can be arranged, likewise enabling contribution to the miniaturization of the device.
The present invention is characterized in that the switch-back means has second housing means for temporarily guiding a sheet to be inverted.
Thereby, in switching-back a sheet, the sheet can be switched-back in an adequate attitude without being hung down.
The present invention is characterized in that the switch-back means discharges a sheet not inverted to the second housing means. Thereby, the space necessary for the switch-back can be utilized as means for discharging and housing the sheet, thus providing merits of increasing the sheet housing capacity, or capable of sorting and housing sheets.
The image forming apparatus according to the present invention is characterized by the provision of the sheet post-treatment device according to claims 1 to 6.
Thereby, there can provide merits that as the entire image forming apparatus provided with the sheet post-treatment device, miniaturization can be achieved; and occurrence of jam is suppressed, and even if the jam should occur, releasing thereof is easy.